Means for indicating load unbalance in multiple anode current ionic valves



March 1966 CARL-ERIK ENGSTRC'JM 3,239,762

MEANS FOR INDICATING LOAD UNBALANCE IN MULTIPLE ANODE CURRENT IONICVALVES Filed NOV. 5, 1963 INVENT R. C. ARL-ERIK gn g ala -W UnitedStates Patent 3,239,762 MEANS FOR INDICATING LOAD UNBALANCE IN MULTIPLEANODE CURRENT IONIC VALVES Carl-Erik Engstriim, Ludvika, Sweden,assignor to Allmiinna Svenska Elektriska Aktiebolaget, Vasteras, Sweden,a corporation of Sweden Filed Nov. 5, 1963, Ser. No. 321,630 Claimspriority, application Sweden, Nov. 29, 1962, 12,822/ 62 2 Claims. (Cl.3288) In converters of the ionic valve (current rectifier) type havingseveral parallel-connected anodes which must ignite simultaneously thereis a risk of unequal distribution of the current, i.e. one anode mayreceive current greater than any of the others. If this unequaldistribution is noticeably large and also continues for a long time itmay lead to overloading and damage to the anode. It is of coursepossible to connect over-current relays in each anode conductor and oneach relay arrange an optical or acoustic signal or a combination ofboth, which is emitted when a fault occurs, but this presupposes thatpersonnel are available to observe the signal. Converter ionic valvesfor high voltage direct current are extremely safe in operation and theionic valve rooms therefore seldom need inspecting by the stationpersonnel. It is thus desirable for a fault of the nature mentioned inthe introduction to be remotely indicated where the personnel are.However, the anodes are situated at a potential of the order ofmagnitude 100 kv. and it is therefore inconceivable to use normaltransmission of the measured value or signals by wires.

The present invention solves the problem by transmitting a signal fromthe high anode potential to earth. According to the invention each anodeis provided with a thermal releasing device influenced by the anodecurrent and with a gas valve controlled by the thermal releasing device,the valve being connected in a tube system of insulating material sothat it can influence the gas pressure in a gas container situated atthe earth potential and provided with a pressure-sensitive measuringmeans.

In the accompanying drawings, FIGURE 1 shows schematically oneembodiment of the invention, while FIGURE 2 shows the gas valve used.

FIGURE 1 shows the invention for use with an ionic valve having fouranodes. The valve housing which contains a cathode or cathodes, isdesignated 1. Each anode is enclosed in an insulator tube positioned onthe valve housing and said anode insulator is surrounded by an outertube 2 of insulating material. The anode insulators support an air drum3 which, together with the tubes 2, forms an air cooling system for theanode insulators. In each anode conduit a thermal releasing device isconnected in parallel. The releasing device consists of a heating bodywhich is heated by a current proportional to the anode current. Thealternation in length of the heating body, through a snap mechanism,controls the releasing arm 6 shown in FIGURE 2 at one end 7 of theheating body. The releasing arm 6 is pivoted at 8 and its other end 9 isarranged to engage a knob 10 acting as a block on a valve rod 12connected to the gas valve 11. In FIGURE 1 the arrangement for theaction of the releasing device on the gas valve 11 is schematicallyindicated by the connection 13.

Into the left-hand gas valve 11a shown in FIGURE 1 a tube 14 opens, madeof an electrically insulating material, preferably plastic. At the otherend the tube is connected to a gas container 15 in which gas, suitablyair, is by means of a pumping means, not shown, maintained at a certainpressure. Thus, the tube 14 acts as an inlet for the gas from thecontainer 15 to the lefthand valve. Inside the valve housing the tube 14ends 3,239,762 Patented Mar. 8, 1966 in a valve seat 16. From the valvehousing an outlet tube 17 leads to the next valve 11b so that the tube17 acts as an inlet to the last mentioned gas valve from the container15. In the same way the valve 11b is connected to the valve 110 by meansof a tube 18 and the valve 11c is connected with the valve 11d by meansof a tube 19. The outlet tube 20 from the valve lid is led to a cylinder21 at the earth potential, said cylinder containing a spring-influencedpiston 22 which is arranged to operate a contact 23.

On the valve rod 12 in the valve housing to the gas valve 11 is attacheda valve plate 24 provided on both sides with seals. A spring 25, whichis arranged between the valve housing and a projection 26 on the valverod, tends to press the valve rod downwards so that the valve plate willabut the valve seat 16 and thus close the inlet tube 14. In its upperposition the valve plate abuts an upper valve seat 27 which is arrangedon an intermediate wall 28 in the valve housing. Between the valve rod12 and the upper valve seat there is a cylindrical channel 29. The valverod is kept in its upper position by the lever 6 which abuts the underside of the knob 10. If the valve rod and valve plate have taken uptheir lower positions because the releasing device 5 has swung thereleasing arm 6 away from the knob 10, the valve rod can be returned toits upper position by a lever 30 and a pullthread 31. In the part of thevalve housing situated above the dividing wall 28 are one or severalholes 32 which join the upper part of the valve housing with the outerair. The releasing device 5 is provided with a flag to indicate thatrelease has taken place.

The arrangement operates in the following way. If the current in any ofthe anode conduits 4, due to unequal loading, exceeds the value set onthe corresponding thermal releasing device 5, the releasing deviceinfluences the lever 6 so that the valve rod 12 is released and thevalve plate 24 is pressed against the valve seat 16 so that the tube 14is shut off from the inside of the valve housing. At the same time asthe valve plate 24 leaves its upper valve seat the tube 17 will beplaced in communication with the open air via the lower part of thevalve housing, the cylindrical channel 29, the upper part of the valvehousing and the holes 32. The pressure in the entire succeeding part ofthe tube system and also in the following gas valves will then drop toatmospheric pressure. The spring in the cylinder 21 presses the piston22 to the left so that the contact 23 closes and a signal is given.

In the embodiment of the invention shown all the gas valves belonging tothe same ionic valve are series-connected. It is of course possible toparallel-connect them to a common feeding tube from the pressurecontainer 15 so that each gas valve with its releasing device operatesand gives signals independently of the others. Other modifications ofthe invention are also conceivable.

I claim:

1. Means for indicating overload current in multiple anode ionic valves,comprising, for each anode, a thermal releasing device responsive tovariations in the anode current and a gas valve controlled by saidthermal releasing device, each said gas valve comprising a valve housingwith inlet and outlet tubes and spring actuated valve means in saidvalve housing operatively connected to said thermal releasing device fornormally connecting the inlet and outlet tubes to each other, said valvemeans including means responsive to a release impulse from said thermalreleasing device for cutting off such connection and establishing aconnection between the outlet tube of such gas valve and the atmosphere,a gas container, means connecting said gas container to the inlet tubeof the valve housing of a first of said gas valves, means connecting theoutlet tube of each gas valve other than the last gas valve to the inlettube of the next gas valve, 21 of said means for establishing theconnection between the pressure sensitive measuring device, and meansconnectoutlet tube and the atmosphere. ing the outlet tube of the lastof said gas valves to said I pressure sensitive measuring device.References C'ted by the Exammer 2. Means according to claim 1, the valvehousing of 5 UNITED STATES PATENTS each gas valve being provided with atleast one gas dis- 2 593 2 0 4 1952 Brown 3 5 charge hole which connectssaid outlet tube to the at- 3,140,852 7/1964 Herzog 251-41 mosphere whensaid valve means cuts 0E the connec- 3,151,834 10/1964 Ray 251-11 tionbetween said outlet and inlet tubes, thereby connecting said pressuresensitive measuring device to the 10 JOHN W'HUCKERTPnmary Examineratmosphere, said gas discharge hole constituting a part KRAFT,ASSi-YtantExaminer-

1. MEANS FOR INDICATING OVERLOAD CURRENT IN MULTIPLE ANODE IONIC VALVES,COMPRISING, FOR EACH ANODE, A THERMAL RELEASING DEVICE RESPONSIVE TOVARIATIONS IN THE ANODE CURRENT AND A GAS VALVE CONTROLLED BY SAIDTHERMAL RELEASING DEVICE, EACH SAID GAS VALVE COMPRISING A VALVE HOUSINGWITH INLET AND OUTLET TUBES AND SPRING ACTUATED VALVE MEANS IN SAIDVALVE HOUSING OPERATIVELY CONNECTED TO SAID THERMAL RELEASING DEVICE FORNORMALLY CONNECTING THE INLET AND OUTLET TUBES TO EACH OTHER, SAID VALVEMEANS INCLUDING MEANS RESPONSIVE TO A RELEASE INPULSE FROM SAID THERMALRELEASING DEVICE FOR CUTTING OFF SUCH CONNECTION